An explosive threat device, once identified as either real or suspected, must be disposed of safely. At present this is commonly done by trained “bomb squad” explosives technicians who are required to dismantle the device and disable its operating components at great risk to themselves and their surroundings.
In addition, the level of equipment and technology available to bomb-makers, whether mentally disturbed persons or actual terrorists, is steadily advancing. In addition to the simple black-powder-and-fuse bombs of the past, bomb technicians must now deal with an increasing variety of explosives, whether commercial such as TNT, dynamite, and pentaerythritol tetranitrate (PETN), or homemade such as triacetone tri peroxide (TATP). These explosives are triggered by an equally expanding variety of initiation mechanisms ranging from simple time fuses to digital watches and cell phones wired to conventional blasting caps with ordinary nine volt batteries. Further, in every case the technician must confront the possibility that in a given threat device there may be more than one trigger mechanism, one of which might be designed to explode upon the mere opening or disassembling of the device.
For these reasons it has been recognized that the most direct and safe way to neutralize a suspected explosive threat device is to destroy it in a controlled explosion. In the past this has been done by transporting the threat to a remote area such as a gravel pit and detonating it there. This has the obvious disadvantages of requiring the threat object to be transported over public roads, and the resulting explosion generally creates a great deal of noise, smoke and flying debris.
A more sophisticated approach to the problem is to destroy the threat by exploding it within a sealed blast chamber using a small remotely detonated donor or booster explosive charge. If the threat device is small enough in terms of estimated weight of explosive, the chamber can be small enough to be carried to the site of the threat on a truck bed or wheeled carriage, which eliminates much of the danger of transporting the object from a public facility and over public roads to a remote location. This approach has been taught by Ohlson, US 2008/0314903 (published Dec. 25, 2008); King, U.S. Pat. No. 7,506,568 (Mar. 24, 2009); and King, U.S. Pat. No. 775,910 (Aug. 3, 2010). Larger, but non-portable, chambers are disclosed by Ohlsson, U.S. Pat. No. 4,478,350 (Oct. 23, 1984); Ohlsson, U.S. Pat. No. 4,632,041 (Dec. 30, 1986); Donovan, U.S. Pat. No. 6,354,181 (Mar. 12, 2002); and Ohlsson US 2990/0044693 (published Feb. 19, 2009).
A principal disadvantage of these prior art devices is that they are necessarily large and bulky because they rely for blast containment on a large internal chamber volume enclosed by a relatively thin spherical chamber body, often of aluminum. While providing greater physical volume can better contain and suppress a controlled detonation, it also requires a larger chamber opening. Such a large opening, while facilitating the loading of a threat device, necessarily results in a greatly increased door surface area. Thus the total separation force from a given internal explosion pressure are equally increased. When combined with relatively weak construction materials and unreliable door-sealing mechanisms, these prior art devices can become unreliable or even dangerous from a safety standpoint. Because of the stresses and deformation that necessarily accompany a detonation of any size (10 lb or TNT or more), certain of these aluminum-body spherical chambers are believed to be one-shot tools at best.
It is therefore a principal object of the invention to provide an improved portable blast-attenuating chamber which is strong, compact, repeatedly usable, and easily transported to the location of a suspected threat device where it can be quickly employed, preferably under remote control, to neutralize the threat either on the spot, or in a nearby safe location.
A further object is to provide a compact self-propelled blast-attenuating chamber capable of being moved quickly in and through the halls and doorways of public buildings, train stations and airports to the location of a suspected threat, and thereafter to a safe nearby area where the threat may be neutralized quickly and without undue danger to personnel or building structure.
Another object is to provide such a chamber with a closure door which is outward-opening for ease of inserting a threat object, and which can be positively locked to the chamber body with moveable locking shoes covering at least 270 degrees of door circumference. A related object is to provide such a door which extends convexly into the body of the chamber, such that it becomes self-tightening with increasing explosion pressures.
Yet another object is to provide a chamber and door in which all the elements of the locking mechanism are interconnected such that each element is mechanically constrained to lock simultaneously with the others, which together with an inhibition signal blocking means, prevents the initiation of detonation of a threat device unless the door is in a fully sealed and locked condition.
A more detailed object is to provide such a chamber and door in which the door is attached to the chamber body in a manner which permits opening and closing in a two-stage operation, with the door being swung into axial alignment with the chamber body in a first stage, and then traversed axially into engagement with the chamber opening in a second stage, whereupon the locking mechanism can be engaged. A related object is to provide self-contained pneumatic operating means for each stage of door operation such that the door must be correctly axially aligned with the chamber prior to insertion, and in which the locking mechanism cannot be actuated until full insertion is achieved.